Since the intensity of irradiated light changes depending on the examination distance in conventional fluoroscopy apparatuses for diagnosing affected regions using fluorescent agents, there is a known method of correcting fluorescence images by dividing a fluorescence-image signal strength by a reference-light-image signal strength (for example, refer to PTL 1).
For an endoscopic apparatus designed to examine autofluorescence, there is a known method of displaying a fluorescence image containing only pixels whose ratio of a fluorescence-image signal strength to a reference-light-image signal strength is larger than or equal to a predetermined threshold such that the position of an affected region is easily located (for example, refer to PTL 2).